definatley tie the calves up for a couple of hours spread out over a couple of days, this will take some of the pull out of them, then put them on the donkey, if you look, you can find people that raise breaking donkeys, and will have them trained a little first. make sure you put them in a place where there is nothing that they can split (one of each side). i always muzzle my donkey, and cut out any ear tags just in case. don't leave the calf on for more than an hour the first day. and make sure that there is not a pile of feed/hay in one place, if you do, the donkey probably won't move enough, lol. good donkeys are like good calves, they are born, not made.